were performed by adding different carbon sources (20 g∙l−1) to the semi-defined medium, SDM [38]: in particular fructose, sucrose, lactose, trehalose and dextrins were used alternatively to analyze how microbial growth and organic acids production were affected. Shake flask experiments were also performed adding sodium lactate (0–60 g∙l−1) at increasing concentrations in the SDM, to evaluate strain growth inhibition. Identification methods Single colonies were collected from MRS plates and characterized with the API 50 CHL system (BioMérieux) according to the manufacturer’s instructions. In order to correctly identify G protein-coupled receptor kinase the Lactobacillus at species level, 16S ribosomal DNA (rDNA) was sequenced [39]. The sequences of the selected Lactobacillus-specific primers LcrisF (AGCGAGCGGAACTAACAGATTTAC) and LcrisR (AGCTGATCATGCGATCTGCTT) confirmed the amplification of a 154-bp fragment of 16S rRNA from the reference strain L. crispatus ATCC33820 [40]. Briefly genomic DNA was extracted from pure cultures using a QIAamp DNA mini kit (Qiagen) according to the manufacturer’s instructions. 4 μl of DNA (≈40 ng), in 50 μl reaction mixtures containing 1× Fast Start High Fidelity PCR system mix (Roche), and 100nM (each) primer were amplified. PCR was performed with the GeneAmp PCR System 9700 (Perkin Elmer, Wellesley, Mass.) with an initial denaturation step of 95°C for 15 min, followed by 40 cycles of 95°C for 15 s and 62°C for 1 min.